Effects of intravenous fentanyl administration on end-tidal sevoflurane concentrations in thoroughbred racehorses undergoing orthopedic surgery.

This research studied the effects of intravenous fentanyl on the concentration of sevoflurane needed in racehorses during orthopedic surgery. Conclusions indicated that the continuous use of IV fentanyl resulted in a lower requirement of sevoflurane in horses.

Methods and Participants

• The study was carried out on 18 thoroughbred racehorses due for orthopedic surgery. These horses were split into two groups. Group SF, comprising of 9 horses, received both sevoflurane and fentanyl, while Group S, also made up of 9 horses, received sevoflurane alone.
• The horses in Group SF were given an initial dose of fentanyl of 5.0 µg/kg over a period of 15 minutes. This was followed by a continuous dose of fentanyl (0.1 µg/kg/min) throughout the surgical procedure.

Results

• Findings showed that the mean end-tidal sevoflurane concentration during the operation in the fentanyl group was significantly lower than that in the group receiving sevoflurane alone. This implies a reduced requirement of sevoflurane for horses that received IV fentanyl.
• Out of the 9 horses in Group SF, plasma fentanyl concentrations remained stable in 7 of them throughout the surgery.
• Additionally, the dobutamine infusion rate required to maintain the horses’ mean arterial blood pressure between 60 and 80 mmHg during the operation was significantly lower in Group SF than in Group S.
• The recovery rate was clinically acceptable, with no severe complications observed in either group.

Conclusion

• The research concluded that the use of continuous IV fentanyl during orthopedic surgery effectively reduced the sevoflurane requirement by 13% in thoroughbred racehorses.
• Despite these positive observations, the study deemed fentanyl as less effective in horses compared to other species. The specific reasons for this assessment, however, were not provided in the abstract.